/*
 * Copyright 2017-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.gitee.minimalismstyle.fresh.common.data.jdbc.beetl

import org.springframework.data.jdbc.core.convert.Identifier
import org.springframework.data.relational.core.sql.SqlIdentifier
import org.springframework.lang.Nullable

/**
 * [BeetlContext] instances get passed to MyBatis mapped statements as arguments, making Ids, instances,
 * domainType and other attributes available to the statements. All methods might return null depending on
 * the kind of values available on invocation.
 *
 * @author Jens Schauder
 * @author Christoph Strobl
 */
class BeetlContext {
    /**
     * The ID of the entity to query/act upon.
     *
     * @return Might return `null`.
     */
    @get:Nullable
    @Nullable
    val id: Any?

    /**
     * The entity to act upon. This is `null` for queries, since the object doesn't exist before the query.
     *
     * @return Might return `null`.
     */
    @get:Nullable
    @Nullable
    val instance: Any?

    /**
     * The [Identifier] for a path to query.
     *
     * @return Might return null.
     */
    @get:Nullable
    @Nullable
    val identifier: Identifier?

    /**
     * The domain type of the entity to query or act upon.
     *
     * @return Might return `null`.
     */
    @get:Nullable
    @Nullable
    val domainType: Class<*>
    private val additionalValues: Map<String, Any>

    constructor(@Nullable id: Any?, @Nullable instance: Any?, @Nullable domainType: Class<*>,
                additionalValues: Map<String, Any>) {
        this.id = id
        identifier = null
        this.instance = instance
        this.domainType = domainType
        this.additionalValues = additionalValues
    }

    constructor(identifier: Identifier?, @Nullable instance: Any?, @Nullable domainType: Class<*>) {
        id = null
        this.identifier = identifier
        this.instance = instance
        this.domainType = domainType
        additionalValues = emptyMap()
    }

    /**
     * Returns a value for the given key. Used to communicate ids of parent entities.
     *
     * @param key Must not be `null`.
     * @return Might return `null`.
     */
    @Nullable
    operator fun get(key: String): Any? {
        var value: Any? = null
        if (this.identifier === null) {
            value = identifier!!.toMap()[SqlIdentifier.unquoted(key)]
        }
        return value ?: additionalValues[key]
    }
}